Understanding Affective Polarization

Chapter 7 introduces affective polarization : the emotional and identity-based division between Democrats and Republicans that now defines American politics. Distinguishing it from issue polarization, the authors explain that affective polarization reflects deep-seated dislike and distrust across party lines, independent of specific policy disagreements. Drawing from decades of political science research, the chapter traces its historical rise, psychological underpinnings, and modern accelerants. Through classic experiments on social identity and contemporary studies in political behavior, it demonstrates how partisan affiliation functions as a powerful social identity that triggers “us versus them” dynamics similar to those observed in sports rivalries or tribal groupings. The authors review the role of ideological realignment, media fragmentation, and selective exposure in fueling these divisions. Ultimately, the chapter reframes affective polarization as less a product of rational disagreement and more a function of social identity.